In wireless power transfer systems, such as wireless charging systems, power is transferred, via e.g., magnetic resonance, from a primary coil of a transmitter to a secondary coil of a receiver. Generally, power is transferred by generating an alternating current flow in the primary coil, which causes a corresponding flow of alternating current in the secondary coil. To generate this alternating current flow in the primary coil, power is often drawn from a direct-current (DC) power source and applied to the primary coil.
Voltage of the DC power source from which the alternating current flow is generated, however, may fluctuate due to mains current frequency, power transfer levels, decoupling capacitance, or other factors. These voltage fluctuations often introduce ripple current in the primary coil, particularly in systems with a single phase AC source where ripple current can be significant. Being coupled to the primary coil, the ripple current is also transferred to the secondary coil where circuitry of the receiver, if passive, further amplifies the amplitude of the ripple current. Passing through circuitry of the receiver, this amplified ripple current can damage current-sensitive components of the receiver, such as batteries, which have specific ripple current limitations.
This description of related art is provided for the purpose of generally presenting a context for the disclosure that follows. Unless indicated otherwise herein, concepts described in this section are not prior art to this disclosure and are not admitted to be prior art by inclusion herein.